ASTM D7039-15a(2020)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D7039 − 15a (Reapproved 2020)
Standard Test Method for
Sulfur in Gasoline, Diesel Fuel, Jet Fuel, Kerosine,
Biodiesel, Biodiesel Blends, and Gasoline-Ethanol Blends
by Monochromatic Wavelength Dispersive X-ray
Fluorescence Spectrometry
This standard is issued under the fixed designation D7039; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 1.6 The values stated in SI units are to be regarded as the
standard. The values given in parentheses are for information
1.1 This test method covers the determination of total sulfur
only.
by monochromatic wavelength-dispersive X-ray fluorescence
1.7 This standard does not purport to address all of the
(MWDXRF)spectrometryinsingle-phasegasoline,dieselfuel,
safety concerns, if any, associated with its use. It is the
refinery process streams used to blend gasoline and diesel, jet
responsibility of the user of this standard to establish appro-
fuel,kerosine,biodiesel,biodieselblends,andgasoline-ethanol
priate safety, health, and environmental practices and deter-
blends.
mine the applicability of regulatory limitations prior to use.
NOTE 1—Volatile samples such as high-vapor-pressure gasolines or
For specific hazard information, see 3.1.
light hydrocarbons might not meet the stated precision because of the
1.8 This international standard was developed in accor-
evaporation of light components during the analysis.
dance with internationally recognized principles on standard-
1.2 Therangeofthistestmethodisbetweenthepooledlimit ization established in the Decision on Principles for the
of quantitation (PLOQ) value (calculated by procedures con- Development of International Standards, Guides and Recom-
sistent with Practice D6259) of 3.2 mg⁄kg total sulfur and the mendations issued by the World Trade Organization Technical
highest level sample in the round robin, 2822 mg⁄kg total Barriers to Trade (TBT) Committee.
sulfur.
2. Referenced Documents
1.3 Samples containing oxygenates can be analyzed with
2.1 ASTM Standards:
this test method provided the matrix of the calibration stan-
D4057 Practice for Manual Sampling of Petroleum and
dards is either matched to the sample matrices or the matrix
Petroleum Products
correction described in Section 5 or AnnexA1 is applied to the
D4177 Practice for Automatic Sampling of Petroleum and
results. The conditions for matrix matching and matrix correc-
Petroleum Products
tion are provided in the Interferences section (Section 5).
D6259 Practice for Determination of a Pooled Limit of
1.4 Samples with sulfur content above 2822 mg⁄kg can be
Quantitation for a Test Method
analyzed after dilution with appropriate solvent (see 5.4). The
D6299 Practice for Applying Statistical Quality Assurance
precision and bias of sulfur determinations on diluted samples
and Control Charting Techniques to Evaluate Analytical
has not been determined and may not be the same as shown for
Measurement System Performance
neat samples (Section 15).
D6300 Practice for Determination of Precision and Bias
Data for Use in Test Methods for Petroleum Products,
1.5 When the elemental composition of the samples differ
Liquid Fuels, and Lubricants
significantly from the calibration standards used to prepare the
D7343 Practice for Optimization, Sample Handling,
calibration curve, the cautions and recommendation in Section
Calibration, and Validation of X-ray Fluorescence Spec-
5 should be carefully observed.
trometry Methods for Elemental Analysis of Petroleum
Products and Lubricants
This test method is under the jurisdiction of ASTM Committee D02 on
Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of
Subcommittee D02.03 on Elemental Analysis. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved May 1, 2020. Published June 2020. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 2004. Last previous edition approved in 2015 as D7039 – 15a. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/D7039-15AR20. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7039 − 15a (2020)
FIG. 1 Schematic of the MWDXRF Analyzer
2.2 EPA Documents: catalyst poisoning, and in the blending of products to com-
40 CFR 80.584 Code of Federal Regulations; Title 40; Part modity specifications.
80; U.S. Environmental Agency, July 1, 2005
4.3 Various federal, state, and local agencies regulate the
sulfur content of some petroleum products, including gasoline
3. Summary of Test Method
anddieselfuel.Unbiasedandprecisedeterminationofsulfurin
3.1 A monochromatic X-ray beam with a wavelength suit-
these products is critical to compliance with regulatory stan-
able to excite the K-shell electrons of sulfur is focused onto a
dards.
test specimen contained in a sample cell (see Fig. 1). The
fluorescent Kα radiation at 0.5373 nm (5.373 Å) emitted by
5. Interferences
sulfur is collected by a fixed monochromator (analyzer). The
5.1 Differences between the elemental composition of test
intensity (counts per second) of the sulfur X rays is measured
samplesandthecalibrationstandardscanresultinbiasedsulfur
using a suitable detector and converted to the concentration of
determinations. For samples within the scope of this test
sulfur (mg/kg) in a test specimen using a calibration equation.
method, elements contributing to bias resulting from differ-
Excitation by monochromatic X rays reduces background,
ences in the matrices of calibrants and test samples are
simplifies matrix correction, and increases the signal/
hydrogen, carbon, and oxygen. A matrix-correction factor (C)
backgroundratiocomparedtopolychromaticexcitationusedin
can be used to correct this bias; the calculation is described in
conventional WDXRF techniques. (Warning—Exposure to
AnnexA1. For general analytical purposes, the matrices of test
excessive quantities of X-ray radiation is injurious to health.
samples and the calibrants are considered to be matched when
The operator needs to take appropriate actions to avoid
the calculated correction factor C is within 0.98 to 1.04. No
exposing any part of his/her body, not only to primary X rays,
matrix correction is required within this range. A matrix
but also to secondary or scattered radiation that might be
correction is required when the value of C is outside the range
present. The X-ray spectrometer should be operated in accor-
of 0.98 to 1.04. For most testing, matrix correction can be
dance with the regulations governing the use of ionizing
avoided with a proper choice of calibrants. For example, based
radiation.)
on the example graph in Annex A1 (Fig. 2), a calibrant with
86 % by mass carbon and 14 % by mass hydrogen can cover
4. Significance and Use
non-oxygen containing samples with C/H ratios from 5.4 to
4.1 This test method provides for the precise measurement
8.5. For gasolines with oxygenates, up to 2.3 % by mass
of the total sulfur content of samples within the scope of this
oxygen (12 % by mass MTBE) can be tolerated for test
test method with minimal sample preparation and analyst
samples with the same C/H ratio as the calibrants.
involvement.Thetypicaltimeforeachanalysisisfiveminutes.
5.2 Fuels containing large quantities of oxygenates, such as
4.2 Knowledge of the sulfur content of diesel fuels,
biodiesel, biodiesel blends, and gasoline-ethanol blends, can
gasolines, and refinery process streams used to blend gasolines
have a high oxygen content leading to significant absorption of
is important for process control as well as the prediction and
sulfur Kα radiation and low sulfur results.
control of operational problems such as unit corrosion and
5.2.1 Biodiesel and biodiesel blends may be analyzed using
this test method by applying correction factors to the results or
using calibration standards that are matrix-matched to the test
Available from U.S. Government Printing Office, 732 N. Capitol Street, NW,
sample(seeTable1).Correctionfactorsmaybecalculated(see
Washington, DC 20401.
Annex A1), or obtained from Table 2 if the sample has been
Bertin, E. P., Principles and Practices of X-ray Spectrometric Analysis, Plenum
Press, New York, 1975, pp. 115–118. measured on a mineral oil calibration curve.
D7039 − 15a (2020)
FIG. 2 Matrix Correction for a Test Sample vs. C/H and Total Oxygen Content Using Chromium Kα for the Excitation Beam
TABLE 1 Methods for Interference Correction by Sample Type
5.4.1 A base material for gasoline can be approximately
Correction simulated by mixing 2,2,4-trimethylpentane (isooctane) and
Tables (Table Correction
toluene in a ratio that approximates the expected aromatic
Matrix
Sample Type 2, Table 3, Calculation
Matching
content of the samples to be analyzed.
Table 4,or (Annex A1)
N/A)
Biodiesel and Biodiesel Blends 2 Yes Yes
6. Apparatus
Gasoline-ethanol Blends 3 or 4 Yes Yes
All Other Sample Types N/A Yes Yes 6.1 Monochromatic Wavelength Dispersive X-ray Fluores-
cence (MWDXRF) Spectrometer , equipped for X-ray detec-
tion at 0.5373 nm (5.373Å).Any spectrometer of this type can
be used if it includes the following features, and the precision
and bias of test results are in accordance with the values
5.2.2 Gasoline-ethanol blends may be analyzed using this
described in Section 15.
test method by applying correction factors to the results or
6.1.1 X-ray Source, capable of producing X rays to excite
using calibration standards that are matrix matched to the test
sulfur. X-ray tubes with a power >25W capable of producing
sample(seeTable1).Correctionfactorsmaybecalculated(see
Rh Lα,PdLα,AgLα,TiKα,ScKα, and Cr Kα radiation are
Annex A1), or obtained from the correction tables. Use Table
recommended for this purpose.
3 if the sample has been measured on a mineral oil calibration
6.1.2 Incident-beam Monochromator, capable of focusing
curve, or use Table 4 if the sample has been measured on an
and selecting a single wavelength of characteristic X rays from
ethanol calibration curve. Ethanol-based calibrants can be used
the source onto the specimen.
for gasoline-ethanol blends. Ethanol-based calibrants are rec-
6.1.3 Optical Path, designed to minimize the absorption
ommended for gasoline-ethanol blends containing more than
along the path of the excitation and fluorescent beams using a
50 % (by volume) ethanol.
vacuum or a helium atmosphere. A vacuum of < 2.7 kPa
5.3 Other samples having interferences as described in 5.1
(<20 Torr) is recommended. The calibration and test measure-
may be analyzed using this test method by applying correction
ments must be done with identical optical paths, including
factors to the results or by using calibration standards that are
vacuum or helium pressure.
matrix matched to the test sample (see Table 1). Correction
6.1.4 Fixed-channel Monochromator,suitablefordispersing
factors may be calculated as described in Annex A1.
sulfur Kα X rays.
5.4 To minimize any bias in the results, use calibration
standards prepared from sulfur-free base materials of the same
The sole source of this apparatus known to the committee at this time is X-ray
or similar elemental composition as the test samples. When
Optical Systems, Inc., 15 Tech Valley Drive, East Greenbush, NY12061. If you are
diluting samples, use a diluent with an elemental composition
aware of alternative suppliers, please provide this information to ASTM Interna-
the same or similar to the base material used for preparing the
tional Headquarters.Your comments will receive careful consideration at a meeting
calibration standards. of the responsible technical committee, which you may attend.
D7039 − 15a (2020)
TABLE 2 Correction Factors for Biodiesel Blends Measured on a Mineral Oil Calibration Curve
NOTE 1—Determine the correction factor in the table below by finding the known oxygen content of the test specimen (for example, 11 wt %) as the
sum of the value in the first column and the value in the first row (for example, 11 = 10+1). The intersection of these two values is the correction factor
(for example, 1.1914). Apply the correction according to 12.5.
Oxygen, wt % 0 % 1 % 2 % 3 % 4 % 5 % 6 % 7 % 8 % 9 %
0 % 1.0000 1.0174 1.0348 1.0522 1.0696 1.0870 1.1044 1.1218 1.1392 1.1566
10 % 1.1740 1.1914 1.2088 1.2262 1.2436 1.2610 1.2784 1.2958 1.3132 1.3306
TABLE 3 Correction Factors for Gasoline-ethanol Blends Measured on a Mineral Oil Calibration Curve
NOTE 1—Determine the correction factor in the table below by finding the known ethanol content of the test specimen (for example, 15 vol %) as the
sum of the value in the first column and the value in the first row (for example, 15 = 10+5). The intersection of these two values is the correction factor
(for example, 1.0881). Apply the correction according to 12.5.
Ethanol, vol % 0 % 1 % 2 % 3 % 4 % 5 % 6 % 7 % 8 % 9 %
0 % 0.9895 0.9962 1.0029 1.0095 1.0161 1.0228 1.0294 1.0360 1.0425 1.0491
10 % 1.0556 1.0621 1.0686 1.0751 1.0816 1.0881 1.0945 1.1009 1.1073 1.1137
20 % 1.1201 1.1265 1.1328 1.1391 1.1455 1.1518 1.1580 1.1643 1.1706 1.1768
30 % 1.1830 1.1892 1.1954 1.2016 1.2077 1.2139 1.2200 1.2261 1.2322 1.2383
40 % 1.2444 1.2504 1.2565 1.2625 1.2685 1.2745 1.2805 1.2865 1.2924 1.2984
50 % 1.3043 1.3102 1.3161 1.3220 1.3279 1.3337 1.3396 1.3454 1.3512 1.3570
60 % 1.3628 1.3686 1.3743 1.3801 1.3858 1.3915 1.3972 1.4029 1.4086 1.4143
70 % 1.4199 1.4256 1.4312 1.4368 1.4424 1.4480 1.4536 1.4591 1.4647 1.4702
80 % 1.4757 1.4813 1.4868 1.4922 1.4977 1.5032 1.5086 1.5141 1.5195 1.5249
90 % 1.5303 1.5357 1.5410 1.5464 1.5518 1.5571 1.5624 1.5677 1.5730 1.5783
TABLE 4 Correction Factors for Gasoline-ethanol Blends Measured on an Ethanol Calibration Curve
NOTE 1—Determine the correction factor in the table below by finding the known ethanol content of the test specimen (for example, 85 vol %) as the
sum of the value in the first column and the value in the first row (for example, 85 = 80+5). The intersection of these two values is the correction factor
(for example, 0.9492). Apply the correction according to 12.5. Refer to 7.8 and 10.1 for ethanol calibration.
Ethanol, vol % 0 % 1 % 2 % 3 % 4 % 5 % 6 % 7 % 8 % 9 %
0 % 0.6248 0.6291 0.6333 0.6375 0.6417 0.6459 0.6500 0.6542 0.6583 0.6625
10 % 0.6666 0.6707 0.6748 0.6789 0.6830 0.6871 0.6912 0.6952 0.6993 0.7033
20 % 0.7073 0.7113 0.7153 0.7193 0.7233 0.7273 0.7313 0.7352 0.7392 0.7431
30 % 0.7470 0.7510 0.7549 0.7588 0.7627 0.7665 0.7704 0.7743 0.7781 0.7820
40 % 0.7858 0.7896 0.7934 0.7972 0.8010 0.8048 0.8086 0.8124 0.8161 0.8199
50 % 0.8236 0.8274 0.8311 0.8348 0.8385 0.8422 0.8459 0.8496 0.8533 0.8569
60 % 0.8606 0.8642 0.8679 0.8715 0.8751 0.8787 0.8823 0.8859 0.8895 0.8931
70 % 0.8967 0.9002 0.9038 0.9073 0.9108 0.9144 0.9179 0.9214 0.9249 0.9284
80 % 0.9319 0.9354 0.9388 0.9423 0.9458 0.9492 0.9527 0.9561 0.9595 0.9629
90 % 0.9663 0.9697 0.9731 0.9765 0.9799 0.9833 0.9866 0.9900 0.9933 0.9967
6.1.5 Detector, designed for efficient detection of sulfur Kα all reagents conform to the specifications of the Committee on
X rays. Analytical Reagents of the American Chemical Society where
6.1.6 Single-Channel Analyzer, an energy discriminator to such specifications are available. Other grades may be used,
monitor only sulfur radiation. provided it is first ascertained that the reagent is of sufficiently
6.1.7 Removable Sample Cell, an open-ended specimen high purity to permit its use without lessening the accuracy of
holder compatible with the geometry of the MWDXRF spec- the determination.
trometeranddesignedtousereplaceableX-raytransparentfilm
7.2 Calibration-Check Samples, for verifying the accuracy
(see 6.1.8) to hold a liquid specimen with a minimum depth of
of a calibration. The check samples shall have known sulfur
5 mm. The sample cell must not leak when fitted with X-ray
content and not be used in determining the calibration curve.A
transparent film. A disposable cell is recommended.
standard from the same reliable and consistent source of
6.1.8 X-Ray Transparent Film, for containing and support-
calibration standards used to determine the calibration curve is
ing the test specimen in the sample cell (see 6.1.7) while
convenient to check the calibration.
providing a low-absorption window for X rays to pass to and
7.3 Di-n-butyl Sulfide, a high-purity liquid with a certified
from the sample. Any film resistant to chemical attack by the
sulfur concentration. Use the certified sulfur concentration
sample, free of sulfur, and X-ray transparent can be used, for
example, polyester, polypropylene, polycarbonate, and poly-
imide.However,samplesofhigharomaticcontentcandissolve
polyester and polycarbonate films. ACS Reagent Chemicals, Specifications and Procedures for Reagents and
Standard-Grade Reference Materials, American Chemical Society, Washington,
7. Reagents and Materials DC. For suggestions on the testing of reagents not listed by theAmerican Chemical
Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset,
7.1 Purity of Reagents—Reagent grade chemicals shall be
U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharma-
used in all tests. Unless otherwise indicated, it is intended that copeial Convention, Inc. (USPC), Rockville, MD.
D7039 − 15a (2020)
when calculating the exact concentrations of sulfur in calibra- 7.11 Polysulfide Oil, generally nonylpolysulfides containing
tion standards. (Warning—Di-n-butyl sulfide is flammable a known percentage of sulfur diluted in a hydrocarbon matrix.
and toxic. Prepared solutions may not be stable several months (Warning—May cause allergic skin reactions.)
NOTE 7—Polysulfide oils are high molecular weight oils that contain
after preparation.)
high concentrations of sulfur, as high as 50 % by weight.
NOTE 2—It is essential to know the concentration of sulfur in the
di-n-butyl sulfide, not only the purity, since impurities can also be 8. Sampling and Sample Handling
sulfur-containing compounds. The sulfur content may be determined via
8.1 Sample fuel according to the procedures in Practices
mass dilution in sulfur-free white oil followed by a direct comparison
D4057 or D4177
analysis against NIST (or other primary standards body) reference
materials.
8.2 Use the utmost care in sampling and handling gasoline
7.4 Drift-Monitor Sample (Optional), to determine and
to prevent evaporation of light ends which could change the
correct instrument drift over time (see 10.4, 11.1, and 12.1).
concentration of sulfur in the sample. Store gasoline in a leak
Various forms of stable sulfur-containing materials are suitable
tight container at 0 °C to 4 °C until ready for analysis. If
drift-correction samples, for example, liquid petroleum, solid,
possible, maintain at this temperature throughout any transfer
pressed powder, metal alloy, and fused glass. The count rate
andhandlingprocesses.Allowspecimensmaintainedat0 °Cto
displayed by the monitor sample, in combination with a
4 °C to reach room temperature before testing, and expose
convenient count time (T), shall be sufficient to give a relative
these materials to ambient conditions only as long as necessary
standard deviation (RSD) of<1% (see Appendix X1).
to obtain a sample for analysis.Analyze test specimens as soon
as possible after sub-sampling from bulk container. Do not
NOTE 3—Calibration standards may be used as drift-monitor samples.
Because it is desirable to discard test specimens after each determination, allow bulk container to remain uncovered any longer than is
alowercostmaterialissuggestedfordailyuse.Anystablematerialcanbe
needed to obtain desired sub-samples.
used for daily monitoring of drift.
8.3 For each sample, an unused piece of X-ray film is
NOTE 4—The effect of drift correction on the precision and bias of this
test method has not been studied.
required for the sample cell. Avoid touching the inside of the
sample cell, any portion of the film exposed to the liquid or the
7.4.1 Drift correction can be done automatically if the
X-ray beam, and also avoid touching the instrument window.
instrument embodies this option, although the calculation can
(It is highly recommended that clean, disposable rubber or
be readily done by conventional methods of data reduction and
plastic gloves be used when preparing test specimens.) Oil
processing.
from fingerprints on the film and wrinkles in the film can
7.5 Quality-Control (QC) Samples, for use in establishing
generate errors in the analysis of sulfur. Therefore, make sure
and monitoring the stability and precision of an analytical
the film is taut and clean to ensure reliable results. Use
measurement system (see Section 14). Use homogeneous
calibration-check samples (see 7.2) to verify calibration integ-
materials, similar to samples of interest and available in
rity if the type and thickness of the window film is changed.
sufficient quantity to be analyzed regularly for a long period of
After the sample cell is filled, provide a vent above the sample
time
to prevent bowing of the film by accumulating vapors. When
NOTE 5—Verification of system control through the use of QC samples
reusable sample cells are used, thoroughly clean and dry cells
and control charting is highly recommended.
before each use. Disposable sample cells shall not be reused.
NOTE 6—Suitable QC samples can be prepared by combining retains of
typical samples.
8.4 Becauseimpuritiesandthicknessvariationscanoccurin
commercially available transparent films and vary from lot to
7.6 White Oil, use a high purity mineral oil and account for
lot,usecalibration-checksamples(see7.2)toverifycalibration
its sulfur content when calculating the sulfur concentrations of
integrity after starting each new batch of film.
the calibration standards.
7.7 Helium, minimum purity 99.9 %, for use as an optical
9. Preparation of Apparatus and Specimens for Analysis
path.
9.1 Analyzer Preparation—Ensure that the MWDXRF ana-
7.8 Ethanol, use a high purity grade and account for its
lyzer has been installed and put into operation according to
sulfurcontentwhencalculatingthesulfurconcentrationsofthe
manufacturer’s instructions. Allow sufficient time for instru-
calibration standards. (Warning—Ethanol is flammable and
ment electronics to stabilize. Perform any instrument checkout
harmful if swallowed or inhaled. It is an eye irritant and may
procedures required. When possible, the instrument should be
cause skin irritation.)
run continuously to maintain optimum stability.
9.1.1 Use the count time (T) recommended by the instru-
7.9 2,2,4-Trimethylpentane (Isooctane), use a high purity
ment manufacturer for the lowest sulfur concentration ex-
grade and account for its sulfur content when calculating the
pected. The typical time for each measurement is two to three
sulfur concentration of the calibration standards. (Warning—
minutes.
Isooctane is flammable and harmful if swallowed or inhaled. It
9.1.2 Alternatively, determine T expected for a desired
is an eye irritant and may cause skin irritation.)
count precision by following the procedure in Appendix X1.
7.10 Toluene, use a high purity grade and account for its
sulfur content when calculating the sulfur concentration of the 9.2 Specimen Preparation—Prepare a specimen of a test
calibration standards. (Warning—Toluene is flammable and sample or a calibration standard as follows:
harmful if swallowed or inhaled. It is an eye irritant and may 9.2.1 Carefully transfer a sufficient portion of the liquid to
cause skin irritation.) fill an open-ended sample cell above a minimum depth of
D7039 − 15a (2020)
TABLE 5 Recommended Sulfur Standard Concentration Ranges
S = mass fraction of sulfur in the prepared standards,
mg/kg,
NOTE 1—Use the calibration range that brackets the expected sample
concentrationrange.Forexample,itisnotnecessarytocalibrate0 mg⁄kg
DBS = actual mass of
...